Spend money on the big-ticket camping items that ensure your comfort and safety. Don't spend money on all the little stuff that can often be better handled by supplies you already own.
Cotton Balls and Vaseline: Hands down the most effective and easiest to use fire starter there is. Also the cheapest. Just shove a handful of cotton balls in a plastic baggie, shove a handful of petroleum jelly in there with them, seal it up and mix them around. Carry them in the same baggie, just push the air out first. The Vaseline will keep water out and burns for about two minutes per-ball. To light, just pull one apart and hit the exposed cotton fibres with a spark or flame from any source. Two-minutes of four-inch high flame is all any fire should need to get going. You can also use dryer lint in place of cotton balls.
Vaseline also works great as a barrier against harsh winter conditions. Rub some on your face before you go climb a frigid glacier. It can also help heal chapped lips, dry skin and can do all those same things for your dog's paws too; rub some into them before taking them outside in the winter.
Bleach: Works great as a water purifier. Just put two drops in your water bottle and shake it up. Bleach won't kill crypto, but be careful of your water sources and that shouldn't be a huge issue. MAKE SURE YOU USE THE UNSCENTED KIND. Plain bleach only.
Cat Food Can: Makes the world's cheapest, lightest and easiest stove.
Old Pill Bottles: Perfect for carrying small quantities of cooking ingredients like oil or spices or such.
Garbage Bags: The bigger and tougher the better. Turn the bag upside down and, on one of the seams just below a corner, cut a hole for your face. Lower down on each side, poke a hole for your arms. Voila, you've got a rain jacket that's virtually free, includes a hood and covers your pack as you wear it too.
Soda Bottles: Plastic one and two-litre soda bottles are rugged and light, making them perfect water bottles for the trail. Put some warm water and dish soap inside, tighten the cap and shake them up to get that hydrogenated corn oil taste out first.
Styrofoam Cups and Paper Plates/Bowls: Want vessels to eat and drink out of that are a) as light as possible b) insulate hot liquids and c) are easy to dispose of? Well, you can't do any better than these.
Bubble Wrap: The world's lightest, cheapest sleeping pad. Some dedicated ultralight backpackers swear by it, but you've got to replace it every few nights.
Tyvek: Have some left over from a home insulation project? Cut a piece to size and use it as a ground cloth or tarp (pictured above).
Duct Tape: Can fix anything. Wrap your water bottle in it to save space.
Aluminium Foil: Makes a light, effective, customisable wind barrier/heat focuser for any stove and you can craft it into cookware. My favourite backpacking meal involves ground beef, sliced potatoes, carrots and onions, packed into two layers of aluminium foil and frozen the night before I leave. To cook it, just throw it in your campfire's coals. http://indefinitelywild.gizmodo.com/how-to-build-y...
Condoms: Make a super packable water storage solution for emergencies. Shove some in your Altoids tin survival kit just in case. Make sure you use the non-flavored, non-lubricated kind.
Freezer Bags: Organise your clothes by days, layers or whatever by packing them into freezer bags and squeezing the air out. Keeps everything dry and organised in your backpack. In a pinch, a freezer bag full of water left out in the sun for a day will kill most bugs that may be in it.
Bread Bags: Cold feet? Step into a pair of bread bags outside your socks, but inside your shoes. They will create a vapor barrier that will hold warmth in.
Bed Sheets: You can turn a pair of bed sheets into a cheap hammock. Here's instructions. You can also grab some silicone from Home Depot and make one into a waterproof tarp.
WD40: Wipe a thin layer onto your big survival knife before you go to help prevent corrosion and reduce friction as you pound that knife through logs. Use it to clean any metal gear (especially anything with folding parts) when you get home. Don't use it on anything that will touch food.
Chocolate: The best comfort/performance food for the outdoors, bar none.
Safety Pins: Stuff breaks. Sometimes that stuff is fabric, straps, your fly, a button or anything else that can easily be fixed with a safety pin.
Super Glue: Got a nasty cut? Pinch it shut and wipe super glue across its surface. Voila, instant stitches. Will fix shoes, boots and most other things too.
Tea Candles: Yes, the ones you buy from Ikea. Stick 'em in a little Mason Jar to make a great lantern.
Avon Skin So Soft: Keeps bugs off, doesn't put disgusting chemicals on your body's largest organ.
Coconut Oil: Melt it, put it in a spray bottle and coat your dog in it to keep him from getting ticks.
Butter: Makes freeze-dried backpacking meals taste better and gives you energy.
What household items do you take camping?
Pictures: Chris Brinlee Jr